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Mitosis & Meiosis

Mitosis & Meiosis. SBI 3U Ms.Zafar November 29 th , 2012. Mitosis. The cells of a multicellular organism are formed through mitosis Differentiation  responsible for differences among cells Takes place in somatic cells. Mitosis.

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Mitosis & Meiosis

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  1. Mitosis & Meiosis SBI 3U Ms.Zafar November 29th, 2012

  2. Mitosis The cells of a multicellular organism are formed through mitosis Differentiation responsible for differences among cells Takes place in somatic cells

  3. Mitosis Diploid number: number indicating the complete set of chromosomes

  4. Mitosis & Cancer Cancer: a group of diseases characterized by abnormal cell division Different from normal cells in 2 ways: -uncontrolled division -continue to divide and pile up on each other  creating a tumour

  5. Mitosis & Cancer Malignant vs. benign Metastasis dangerous. Can move through body and invade new tissues

  6. Mitosis & Cancer Treatment options: -Radiation therapy – directed at specific sites within the body to kill cancer cells -Chemotherapy – drugs -Immunotherapy – using the body’s own natural defences

  7. Meiosis

  8. Meiosis Meiosis is a special type of cell division necessary for sexual reproduction in eukaryotes Meiosis prevents the doubling of chromosomes when gametes unite

  9. Chromosome Number & Structure 23 pairs of homologous chromosomes 2 in a pair – 1 one from mother and 1 from father Maternal set vs. Paternal set Each homolog carries the same hereditary traits as its partner

  10. Chromosome Number & Structure Info for specific traits stored as genes Each gene is located at a locus Alleles: different forms of genes

  11. Chromosome Number & Structure # of chromosomes in each gamete is one-half of the diploid number  called the haploid number Fertilization results in the joining of 2 haploid gametes to make a single diploid cell called the zygote

  12. Stages of Meiosis Meiosis occurs only in reproductive tissues 2 major divisions – Meiosis I and Meiosis II

  13. Meiosis I – Prophase I Genetic material has been replicated before Meiotic division Chromosomes become visible Synapsis: homologous chromosomes come together Tetrad: 4 chromatids together Chiasmata and crossing over

  14. Metaphase I Tetrads have moved to the equator

  15. Anaphase I Chromatids do not split – instead the chromosomes move apart from each other

  16. Telophase I Chromosomes condense slightly and a nuclear membrane forms 2 daughter cells result  half the number of chromosomes Reduction division

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